2b.7b

Question 1

Define submergent coastline

Answer 1

sections of the littoral zone where sea level rise inundated areas that were previously part of terrestrial land

Question 2

Define fossil cliff

Answer 2

a steep slope found at the back of a raised beach exhibiting evidence of formation through marine erosion but now above high tide level.

Question 3

Define eustatic sea level rise

Answer 3

global sea-level changes related either to changes in the volume of glacial ice on land or to changes in the shape of the sea floor caused by plate tectonic processes

Question 4

Explain eustatic (isostatic?..) sea level change as a result of tectonic activity

Answer 4

Faulting and folding of crust can create displacement of seabed (e.g. Sumatra since 2004 Earthquake, or Dalmatian coast in Croatia)

Question 5

Explain eustatic sea level change as a result of post glacial period

Answer 5

• Sea level rise approx. 125 m since the last Glacial Maximum (LGM) – 21,000 years ago!
• Meltwater pulse around 14,000 years ago – most ice melted by 6,000 years ago and sea level is now only slowly rising.

Question 6

What creates submergent coastlines

Answer 6

sea level changes

Question 7

State three submergent coastline landforms

Answer 7

rias, fjords and dalmation coasts

Question 8

What is a fjord

Answer 8

Submerged (flooded glaciated u shaped valley) U-shaped valley that has been over-deepened inland. Rock lip threshold exists at seaward entrance.

Question 9

Where are fjords found?

Answer 9

Also found in Norway (e.g. Sognefjorden), New Zealand, Chile, Alaska, and Greenland.

Question 10

What is a ria

Answer 10

• Drowned (flooded river valley) valley due to river erosion (outside LGM ice extent) – e.g. Kingsbridge Estuary
• dorwned by rising sea levels
• Rivers eroded steep-sided V-shaped valleys into the frozen landscape giving the ria a V-shaped cross section when the valley flooded

Question 11

Where are rias found

Answer 11

Also found SW Wales, Ireland (e.g. Cork), Brittany and NW Spain

Question 12

State an example of a submergent coastline

Answer 12

Sognefjorden, Norway

Question 13

Describe the fjord in norway

Answer 13

Largest Fjord system in Norway – extends 200 km inland from west coast
Alignment corresponds to fracture system in bedrock (exploited by rivers, then glaciers)
Main Fjord basin is at a depth of ~800m below present sea levels (although deepest point is 1308m bsl)
Entrance at seaward end is shallower (100-150m) due to a rock bar (threshold)

Question 14

Define emergnet coastline

Answer 14

Emergent coastlines are being produced by post-glacial adjustment. These are parts of the littoral zone where a fall in sea level exposed land once part of the sea bed

Question 15

State three characteristics of a raised beach

Answer 15

• A relict beach now above high tide level
• A flat surface covered by sand or rounded pebbles/boulders.
• Usually vegetated by plant succession (though further succession prevented due to grazing)

Question 16

Comapre shapes of rias and fjords

Answer 16

• Rias have a sinuous plan profile reflecting the meandering river course. The plan view is dendritic as tributies are flooded by the rising sea.
• Fjords often have a relatively straight profile as glaciers truncate spurs to produce a direct downslope route.
• Glacier erosion is often cut deep into the landscape, often tens of metres lower than the adjacent unglaciated land - meaning that fjords are often deeper than the adjacent sea.

Question 17

Why do fjords and rias occur

Answer 17

Isostaic rebound - areas that were adjacent to glaciated areas sink down during marine transgression